Honda BF50A Cooling Problems

Hi Gang,

Its the apprentice again! Hope all is well with all you forum goers. My motors have been doing quite well since my last challenges. However, I have encountered another problem. I know coming here will help me so here goes:

One of my 50's overheating buzzer started coming on. So I ran through the process of elimination. Had the motor flushed with lime away, motor pees really good except when you accelerate the engine. So I checked the empeller and all is fine and still the same problem. When I get up to about 3100 rpms the warning buzzer comes on and when I return below 3100 rpms the buzzer goes off. During this I notice the water coming out of the pee hole warms up and cools down.I also notice that the water coming out of the pee hole does not increase as the motor accelerates. The stream stays the same.

I replace the entire leg component and the problem went away. Luckily I have spare legs to do this. So obviously the problem lies in the leg. Can the pump or other component in the leg go bad? I would like to repair it if possible. Any words of advice???

Thanks

I'd guess that your impeller is either missing teeth or taken a 'set'. It provides enough cooling for lower RPMs, but not enough for higher RPMs.

Recommend changing out the entire water pump, not just the impeller. Open up the old pump and inspect the impeller. If teeth are missing, they may clog up your water system, so remove the t-stats and reverse flush the water passages.

The impeller is in good shape. No teeth missing. I will change out the pump. Also did flush out the water passage. But not sure what process you are talking about when you say "t-stat". This is how I flush;

Remove the leg, attach a bilge pump/hose to the water inlet tubing. The bilge pump is submerge in a container with limeaway (a solution that disolves salt and corrosion build up). The solution is sent up through the water inlet tube and through the engine, then out the pee hole then back into the container causing a circulating system. The solution is then replace depending on how much junk comes out and the process repeated.

Can you explain the t-stats and reverse flush system?

What you are doing is much better than I suggested. Typically, you just remove the t-stat and insert a garden hose, stuff a rag around it for a decent seal, then turn it on for about 15 - 20 minutes. I like your method a lot better.

Ohhh!! got it. t-stat stands for thermo stat. Yeah. I know this would be a more simple remedy. Mine has been effective but it means removing the leg. I will keep this in mind. Also here in Hawaii the weather never changes much like it does in the states so I actually remove the t-stat which actually helps the motor run a lot cooler. Plus the salt water can tend to corrode the t-stat pretty quick making it non functionable. My motors have done well without the t-stat in them. I will work on the pump itself as it actually seems to be the focus of my problem. Will let you all know the outcome.

Thanks for all the assistance.
Happy boating.

Well, okay on running without the t-stat installed, but I have some serious reservations about that. Four strokes especially are designed to run at a specific operating temperature. Not sure what temperature your 50 is supposed to be operating, but I certainly would check the owners manual - it's likely between 160 to 180 degrees F. If they are run cooler than designed, you are wearing out the rings, cam, and cam bearings faster, your fuel efficiency is sub-optimal, and your timing will be slightly off. You can compensate with a thinner oil, but it's a total guess on how much thinner.

Personally, I'd re-install the t-stats and just make sure I checked them often.

Would like to see some of the real experts jump in on this one.

Thanks for the great insight. Thats why I like this forum. You get experience that the manual doesn't cover. I was just reading on another forum (McGregor Yatchts) and they were discussing similar cooling issues with enlarging the water indicator outlet.

What are your thoughts about enlarging the water outlet?

Thanks again.

The operating temperature depends on the year of the motor....through 2003 the thermostat opens fully at 162 F. After 2003, it fully opens at 144 F. Even in the warm waters of Hawaii, i doubt either motor will get to proper operating temperature without a thermostat.

I agree with chawk_man, the engine needs to get to proper operating temperature in order to operate efficiently. As an incentive to putting up with checking thermostat regularly, just keep in mind that you will be burning less fuel and your engine will run better and smoother.

As far as enlarging the water outlet...no harm in that, we do it to workboats all the time that are running in debris. Your limitation will be the nipple coming out of the engine. Most just eliminate the nipple going through the engine cover and just put the hose through the hole. A snug but not too tight wire tie will keep it from going back in the hole.

If the indicator gets plugged, it will not affect the cooling of the engine. You just will not see that the water is pumping.

Mike

Thanks again you guys. Great insight. I will install the t-stat back.+ Reply to Thread

Good morning Honda Enthusiasts,

I installed the t-stats back, made couple of fishing runs. I notice that the water coming out of the pee hole has more pressure making circulation better (I believe the pressure and temp build up as the result of the t-stat). Pee hole water is nice and warm (not hot). I also change from ethanol to ethanol-free gas. motors are running a lot smoother. Thanks again for the advice and insight. I truly appreciate all the expertise this forum offers. You can't get this kind of advice from anyone here in Hawaii. Helps on my finances given the fact that owning a boat is expensive to begin with. Thanks again. I'm sharing my experience with this forum with my friends who own Hondas.

Good to hear that you are up and operating in good form.